diff --git a/BUILD b/BUILD
index c02fb9d5b31..642b6c4e2aa 100644
--- a/BUILD
+++ b/BUILD
@@ -438,6 +438,9 @@ cc_library(
     "//external:zlib",
     ":gpr",
   ],
+  copts = [
+    "-std=gnu99",
+  ],
 )
 
 
@@ -707,6 +710,9 @@ cc_library(
   deps = [
     ":gpr",
   ],
+  copts = [
+    "-std=gnu99",
+  ],
 )
 
 
diff --git a/templates/BUILD.template b/templates/BUILD.template
index bb18c353b10..54dc6971252 100644
--- a/templates/BUILD.template
+++ b/templates/BUILD.template
@@ -104,6 +104,11 @@
       "${dep}",
   % endfor
     ],
+  % if lib.name in ("grpc", "grpc_unsecure"):
+    copts = [
+      "-std=gnu99",
+    ],
+  % endif
   )
   </%def>